• 한국산림과학회지
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• 제56권1호
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• pp.77-81
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• 1982

4수종(樹種) 열대산활엽수재(熱帯産闊葉樹材) Xylan의 성상(性状)을 분석(分析)하였다. Xylan은 24% KOH로 추출(抽出)하였으며 ethanol 적하법(適下法)으로 정제(精製)하고, Uronic acid잔기(残基), methoxyl기(基) 및 acetyl기(基)의 함유량(含有量)과 점도법(粘度法)에 의하여 중합도(重合度)를 측정(測定)하였다. Uronic acid잔기(残基)에 대한 Xylan잔기(残基)의 비(比)는 Xylan함유율(含有率)이 온대산활엽수재(温帯産闊葉樹材)의 그것과 비슷한 mangrove재(材)의 경우만이 온대산활엽수재(温帯産闊葉樹材)의 그것과 필적(匹敵)하는 높은 값을 나타내었다. Methoxyl기(基)도 Uronic acid잔기(残基) 함유량(含有量)의 결과(結果)와 동일(同一)하였다. DMSO추출(抽出) Xylan중(中)에는 D-xylose잔기(残基)이외의 Hemicellulose도 다수(多数) 함유(含有)되어 있으며, acetyl기량(基量)은 MDX 5.4%, RDX 6.8%로 xylose 잔기(残基) 5~6개당(個当) 1개(個)이고, DMSO추출(抽出) 된지 않은 Xylan에는 acetyl기(基)가 존재(存在)하였다. 점도법(粘度法)에서 측정(測定)한 $\bar{P}_n$는 200전후(前後)로 온대산활엽수재(温帯産闊葉樹材)와 비슷하였고, Uronic acid잔기(残基)로 계산(計算)한 $\bar{DP}n$ 열대산활엽수재(熱帯産闊葉樹材)와 비슷하였다.

• Biomolecules & Therapeutics
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• 제20권4호
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• pp.371-379
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• 2012

Prebiotic oligosaccharides, with a degree of polymerization (DP) of mostly less than 10, exhibit diverse biological activities that contribute to human health. Currently available prebiotics are mostly derived from disaccharides and simple polysaccharides found in plants. Subtle differences in the structures of oligosaccharides can cause significant differences in their prebiotic properties. Therefore, alternative substances supplying polysaccharides that have more diverse and complex structures are necessary for the development of novel oligosaccharides that have actions not present in existing prebiotics. In this review, we show that structural polysaccharides found in plant cell walls, such as xylans and pectins, are particularly potential resources supplying broadly diverse polysaccharides to produce new prebiotics.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2011년도 춘계학술발표회 논문집
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• pp.169-169
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• 2011

Xylans are polysaccharides present in large amounts in cell walls of land plants. However, during kraft cooking, a high portion of hemicelluloses including xylans are dissolved in the cooking liquor. In the current trend for a more effective utilization of biomass, attention has been paid to the exploitation of xylans as strength-enhancing additives for paper. It is believed that surface xylan adds flexibility to the cell wall/fiber surface, resulting in stronger fiber-fiber joints or greater contact area between the fibers. Accordingly, there is proposal for a new pulping process involving the extraction of xylan prior to pulping, followed by their re-adsorption on the unbleached pulp. A suitable bleaching process should be employed then, which ought to does not only improve the brightness of the pulp, but also remain the effect of the adsorption of xylan on pulp fibers. The objective of this research was to investigate the impact of hydrogen peroxide bleaching on the properties of unbleached hardwood kraft pulp pretreated with birchwood xylan by measuring optical properties (brightness, post color number, opacity) as well as physical properties (tensile index, tearing index, bulk) of handsheets made from the bleached pulp. In the meantime, the influence of process variables of peroxide bleaching including bleaching temperature, time, initial pH and $MgSO_4$ dosage were studied.

• 한국미생물·생명공학회지
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• 제44권3호
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• pp.324-332
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• 2016

왕겨를 탄소원으로 사용하여 증균 배양을 실시함으로써 국내 사찰에서 제조된 된장으로부터 xylan 분해능 우수한 균주를 분리하였다. 분리균 YB-1301은 DNA gyrase subunit B 유전자(gyrB)의 염기서열에 근거하여 Bacillus safensis로 동정되었다. B. safensis YB-1301을 밀기울 또는 여러 종류의 xylan들이 첨가된 배지에서 배양하였을 때 xylanase의 생산성이 급격하게 증가되었다. 특히 birchwood xylan이 첨가된 LB 배지에서 플라스크 배양을 하였을 때 최대 340 U/ml 이상의 xylanase 생산성을 보였다. Xylan이 첨가되지 않은 LB 배지에서는 매우 소량의 xylanase가 균의 성장과 연계되어 항시적으로 생산되지만, xylan이 첨가된 배지에서는 정지기 생육단계에서 xylanase의 생산이 크게 유도되었다. 더구나 xylanase 생합성은 가수분해되지 않은 xylan 보다 xylan의 효소적 가수분해 산물에 의해 더 빠르게 유도되었다. 또한 B. safensis YB-1301의 배양상등액에 존재하는 xylanase는 55℃와 pH 6.5−7.0의 반응조건에서 최대활성을 나타냈다.

• Journal of Microbiology and Biotechnology
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• 제25권9호
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• pp.1476-1484
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• 2015

Three endoxylanase-encoding genes from the moderately themophilic chemoorganotrophic bacterium Melioribacter roseus were cloned and expressed in Escherichia coli. Genes xyl2091 (Mros_2091) and xyl2495 (Mros_2495) encode GH10 family hydrolases, whereas xyl2090 (Mros_2090) represents the GH30 family. In addition to catalytic domains, Xyl2090 and Xyl2091 contain carbohydrate-binding modules that could facilitate their binding to xylans and Por sorting domains associated with the sorting of proteins from the periplasm to the outer membrane, where they are covalently attached. Recombinant endoxylanase Xyl2495 exhibited a high specific activity of 1,920 U/mg on birchwood xylan at 40℃. It is active at low temperatures, exhibiting more than 30% of the maximal activity even at 0℃. Endoxylanases Xyl2090 and Xyl2091 have lower specific activities but higher temperature optima at 80℃ and 65℃, respectively. Analysis of xylan hydrolysis products revealed that Xyl2090 generates xylo-oligosaccharides longer than xylopentaose. Xylose and xylobiose are the major products of xylan hydrolysis by the recombinant Xyl2091 and Xyl2495. No activity against cellulose was observed for all enzymes. The presence of three xylanases ensures efficient xylan hydrolysis by M. roseus. The highly processive "free" endoxylanase Xyl2495 could hydrolyze xylan under moderate temperatures. Xylan hydrolysis at elevated temperatures could be accomplished by concerted action of two cell-bound xylanases; Xyl2090 that probably degrades xylans to long xylo-oligosaccharides, and Xyl2091 hydrolyzing them to xylose and xylobiose. The new endoxylanases could be useful for saccharification of lignocellulosic biomass in biofuels production, bleaching of paper pulp, and obtaining low molecular weight xylooligosaccharides.

• Journal of Microbiology and Biotechnology
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• 제19권3호
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• pp.277-285
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• 2009

The nucleotide sequence of the Paenibacillus curdlanolyticus B-6 xyn10A gene, encoding a xylanase Xyn10A, consists of 3,828 nucleotides encoding a protein of 1,276 amino acids with a predicted molecular mass of 142,726 Da. Sequence analysis indicated that Xyn10A is a multidomain enzyme comprising nine domains in the following order: three family 22 carbohydrate-binding modules (CBMs), a family 10 catalytic domain of glycosyl hydrolases (xylanase), a family 9 CBM, a glycine-rich region, and three surface layer homology (SLH) domains. Xyn10A was purified from a recombinant Escherichia coli by a single step of affinity purification on cellulose. It could effectively hydrolyze agricultural wastes and pure insoluble xylans, especially low substituted insoluble xylan. The hydrolysis products were a series of short-chain xylooligosaccharides, indicating that the purified enzyme was an endo-$\beta$-1,4-xylanase. Xyn10A bound to various insoluble polysaccharides including Avicel, $\alpha$-cellulose, insoluble birchwood and oat spelt xylans, chitin, and starches, and the cell wall fragments of P. curdlanolyticus B-6, indicating that both the CBM and the SLH domains are fully functioning in the Xyn10A. Removal of the CBMs from Xyn10A strongly reduced the ability of plant cell wall hydrolysis. These results suggested that the CBMs of Xyn10A play an important role in the hydrolysis of plant cell walls.

• Journal of Microbiology and Biotechnology
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• 제21권8호
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• pp.861-868
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• 2011

A xylanase gene, xyn7c, was cloned from Paenibacillus sp. 12-11, an alkalophilic strain isolated from the alkaline wastewater sludge of a paper mill, and expressed in Escherichia coli. The full-length gene consists of 1,296 bp and encodes a mature protein of 400 residues (excluding the putative signal peptide) that belongs to the glycoside hydrolase family 10. The optimal pH of the purified recombinant XYN7C was found to be 8.0, and the enzyme had good pH adaptability at 6.5-8.5 and stability over a broad pH range of 5.0-11.0. XYN7C exhibited maximum activity at $55^{\circ}C$ and was thermostable at $50^{\circ}C$ and below. Using wheat arabinoxylan as the substrate, XYN7C had a high specific activity of 1,886 U/mg, and the apparent $K_m$ and $V_{max}$ values were 1.18 mg/ml and 1,961 ${\mu}mol$/mg/min, respectively. XYN7C also had substrate specificity towards various xylans, and was highly resistant to neutral proteases. The main hydrolysis products of xylans were xylose and xylobiose. These properties make XYN7C a promising candidate to be used in biobleaching, baking, and cotton scouring processes.

• Journal of Microbiology and Biotechnology
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• 제6권2호
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• pp.79-85
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• 1996

By using a T7 expression system, a large amount of Bacillus stearothermophilus endo-xylanase A (XynA) could be produced in Escherichia coli cells. The overproduced enzyme formed inclusion bodies, and so the protein could be more easily purified to homogeneity. The molecular weight of the purified enzyme was estimated to be 22 kDa by SDS-polyacrylamide gel electrophoresis and 43 kDa by Sephacryl S-200 gel filtration, suggesting that the native enzyme was a homodimer. The pI value was determined to be 8.4. The Michaelis constants for birchwood xylan and oat spelts xylan were calculated to be 3.83 mg/ml and 5.03 mg/ml, respectively, and the $V_{max}$ max/ values for both xylans were 2.86 $\mu mole$/min. The purified enzyme was most active at $55^{\circ}C$ and pH 8.0, and stable up to $60^{\circ}C$ and in the near neutral pH range. From the zymogram, Bacillus stearothermophilus was found to have at least three xylanases and the purified one was the smallest among them.

• Journal of Microbiology and Biotechnology
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• 제19권12호
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• pp.1514-1519
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• 2009

A gene encoding the xylanase of Bacillus subtilis AMX-4 isolated from soil was cloned into Escherichia coli and the gene product was purified from the cell-free extract of the recombinant strain. The gene, designated xylA, consisted of 639 nucleotides encoding a polypeptide of 213 residues. The deduced amino acid sequence was highly homologous to those of xylanases belonging to glycosyl hydrolase family 11. The molecular mass of the purified xylanase was 23 kDa as estimated by SDS-PAGE. The enzyme had a pH optimum of 6.0-7.0 and a temperature optimum of $50-55^{\circ}C$. Xylanase activity was significantly inhibited by 5 mM $Cu^{2+}$ and 5 mM $Mn^{2+}$, and noticeably enhanced by 5 mM $Fe^{2+}$. The enzyme was active on xylans including arabinoxylan, birchwood xylan, and oat spelt xylan, but it did not exhibit activity toward carboxymethylcellulose or p-nitrophenyl-$\beta$-xylopyranoside. The predominant products resulting from xylan and xylooligosaccharide hydrolysis were xylobiose and xylotriose. The enzyme could hydrolyze xylooligosaccharides larger than xylotriose.

• 펄프종이기술
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• 제40권4호
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• pp.43-50
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• 2008

Adsorption of xylans extracted from birchwood and oat spelt on Hw-BKP were analyzed using HPLC. The effect of xylan adsorption on paper properties such as tensile, tear index and brightness was also investigated. The constituents of xylan was analyzed with HPLC after hydrolysis with dilute sulfuric acid. It was shown that xylose was the major constituent and small amounts of glucose and galactose were contained in the xylan samples. Adsorption of xylan on hardwood fibers was evaluated using acid hydrolysis and HPLC techniques. Results showed that the adsorption of negatively charged xylan on the fiber surface was negligible probably because electrostatic repulsion between these two materials. Pretreatment of the fiber with alum increased xylan adsorption. The amount of adsorption increased up to 30 mg/g. With the increase of xylan adsorption both tensile and tear strength of the handsheet increased suggesting xylan can be a very effective strength agents for papermaking. Brightness of the handsheets decreased, however, with the use of xylan.